More than four billion quarts of crankcase oil are used in the United States per year. Currently available engine oils include the anti-wear additive zinc dialkyldithiophosphate (ZDDP), which contains phosphorous and sulfur. These are elements that poison catalytic converters causing increased automotive emissions. It is expected that the EPA eventually will mandate the total elimination of ZDDP or will allow only extremely low levels of ZDDP in engine oil. However, no acceptable anti-wear additives are currently available to replace ZDDP.
It is an object of the present invention to provide an environmentally friendly anti-wear additive for engine oil, wherein the amounts of phosphorous and sulfur in the anti-wear additive approach zero.